Suscripción a Biblioteca: Guest
TSFP DL Home Archivos Comité Ejecutivo

INCOMPLETE SIMILARITY OF A PLANE TURBULENT WALL JET

Noorallah Rostamy
Department of Mechanical Engineering, University of Saskatchewan 57 Campus Drive, Saskatoon, Saskatchewan, Canada S7N 5A9

Donald J. Bergstrom
Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada

David Sumner
Department of Mechanical Engineering University of Saskatchewan 57 Campus Drive, Saskatoon, Saskatchewan, S7N 5A2, Canada

James D. Bugg
Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan, S7N 5A9, Canada

Sinopsis

Incomplete similarity for a plane turbulent wall jet is reported in this paper. Typically, a wall jet is divided into two regions: an inner layer and an outer layer. The degree to which these two layers reach equilibrium with each other, and produce a self-similar velocity profile remains an open question. In this paper, the theory of Barenblatt et al. (2005), which proposes incomplete similarity, is used to analyse the mean velocity field of a turbulent wall jet based on a new set of laser Doppler anemometry (LDA) measurements. The experiments were carried out in a water tank. The fluid was discharged with a velocity of U0 = 1.21 m/s through a rectangular slot with a height of H = 6 mm. The Reynolds number of the wall jet, based on the jet exit velocity and the slot height, was approximately Re = 7500. The similarity in both the inner and outer regions of the wall jet flow was studied in the nominally fully developed region of the jet, i.e. x/H > 30. The outer and inner half-widths are shown to develop differently in the streamwise direction when scaled with the jet slot width. Using outer scales, a good collapse of the experimental data can be seen in the outer region, while the profiles deviate from each other near the wall. In contrast, using the inner scales collapses the mean velocity profile in the inner region of the wall jet, but not in the outer region.